This application claims priority to PCT Application No. PCT/EP99/09088 filed Nov. 24, 1999, which claims priority to German Patent Application No. 19854191.0 filed Nov. 24, 1998.
The invention concerns a set comprising a plurality of mutually juxtaposed, generally flat, plate-shaped components which are fixedly connected together, and a process for the production thereof.
In industrial uses, it frequently happens that a large number of mutually juxtaposed, often very thin, plate-shaped components have to be handled in conjunction with each other, for example in the bed of a knitting machine or when dealing with knitting members. For that purpose, a plurality of such components are joined together to form a set or array, thereby considerably facilitating handling and in particular replacement thereof. That is an important aspect in particular when the components are wearing parts and accordingly replacement has to be effected relatively frequently. Production from the solid material, for example by means of milling, is often no longer possible or is not economical, in particular when dealing with thin components.
In that respect, there are hitherto known different possible ways of connecting together those components which mostly comprise metal, in particular a carbon-bearing hardenable steel.
In that respect, welding is a rather unusual procedure as the welding temperature required can give rise to distortion of the components and in particular also the welding operation can mean that the relative position of the components with respect to each other can very easily change.
Another option involves individually glueing the components together in succession, but that is also a time-consuming procedure having regard to a large number of components in each set.
It is further known for the components to be joined together to form a set by the components being cast into another material, for example at the free ends of the components. If the demands in regard to load-bearing capability are low, casting can be effected using plastic material, while when a higher load-bearing capability is required the components are cast into a metal alloy with a low melting point, for example a lead alloy, or nickel silver.
A disadvantage here is that the casting material drastically increases the weight of the set, in particular when the components are cast into metal. In that respect, the cast set is not infrequently ten times as heavy as the set without the casting material, precisely when the components are very thin and small items such as for example the needles of a knitting machine.
The disadvantage here is that the casting operation preferably has to be effected at the free ends of the components as a casting procedure in the central region thereof is very much more complicated and in addition it is necessary to take account in regard to the dimensions involved of shrinkage of the casting material upon cooling, which requires a great deal of experience. It is however precisely the free end regions of the components that frequently serve as operational surfaces and have to be freely accessible.
It is further known for the components to be threaded on to dowel or fitting pins by a procedure whereby mutually aligned bores are provided in the components, with the pins being passed through the bores. The desired spacing between the individual components can be achieved by respective interposed spacer sleeves.
A further disadvantage is that the dowel pins required must be produced with very tight dimensional tolerances and are correspondingly expensive. Furthermore, arranging spacer sleeves between the needles in the operation of threading the components on to the pins is a difficult and time-consuming procedure. In addition that situation involves the problem of cumulative error in regard to the spacer sleeves.
It is further known for the components to be threaded on to a fitting tube by a procedure whereby aligned bores are provided in the components, through which the tube is passed. The components are fixed on the tube by subsequently expanding the tube radially outwardly by means of an expanding taper member or by an expanding bar which is pushed through the tube.
The disadvantage here however is that the length of the tube is decreased overall by virtue of expansion thereof, in other words, the initial length of the set does not correspond to the final length thereof, and accordingly the spacings of the components relative to each other are also altered during expansion of the tube. Due to that cumulative error only sets of limited length can be produced.
A further disadvantage is that on the one hand a certain minimum wall thickness and, because of a minimum inside diameter of the tube for the expansion element, thus a certain minimum outside diameter of the tube, are required to afford a sufficiently strong and stable connection. The mechanical loading of the edge regions of the components which are to be threaded on to the tube, around the orifice thereof, also means that the width of the components in the region of the orifices cannot be less than a certain minimum value.
a) Technical Object
Therefore the object of the present invention is to provide a set and a process for the production thereof, wherein production is easy and inexpensive to carry into effect and thus also the entire set can be produced on the one hand inexpensively and on the other hand sufficiently accurately in terms of fit.
b) Attainment of the Object
That object is attained by the features of claims 1 and 24. Advantageous embodiments are set forth in the appendant claims.
The fact that a bar is inserted into the mutually aligned orifices in the components and the bar is then glued to the set of components in such a way that the individual components are fixedly carried on the bar affords marked advantages over the previous fixing methods.
In that respect, the bar used for being pushed through the components must be less accurate in terms of fit than a dowel or fitting pin as it is not the clearance between the outside diameter of the bar in the initial condition and the inside diameter of the orifice in the components that determines the subsequent clearance of motion of the components within the set, as when using a fitting pin.
On the contrary, in making the connection, the individual components only have to be arranged in the correct relative position with respect to each other, more specifically in the desired final position relative to each other. On the one hand, insertion of the bar is a simple procedure as there may be sufficient clearance, approximately between one and five hundredths of a millimeter, between the outside diameter of the bar and the inside diameter of the orifice. On the other hand, the connection to the components is first completed by virtue of glueing to the bar, and thus even minor positional or dimensional deviations in the orifices in the components are compensated thereby. That simplifies and reduces the cost of production of the individual components. In addition the bar itself, in respect of its outside diameter, is only required to satisfy demands which are markedly below the close tolerances of a snugly fitting pin.
For example the diameter of the bar in contrast will change relatively greatly with the size of the components and is at least 4 mm. A usual diameter for components which are of a height of between about 10 and 20 mm is 3 mm.
While the individual components mostly comprise a carbon-bearing, that is to say hardenable steel which however is unhardened when making the connection, such as C80 or C100, a chromium-nickel steel is generally used for the bar.
The fact that no mechanical forces worth mentioning are applied to the clamping components when the bars are being inserted into the mutually aligned orifices or when the set is being glued means that the individual components do not have to be supported in the region of the orifices therethrough, but it is sufficient to position the individual components and fix them in place relative to each other in the functional region thereof. That affords the advantage that even those components which admittedly maintain the required dimensional tolerances such as for example straightness and so forth in the functional region, but not in the region of the orifices, can nonetheless be used as curvature and so forth which occurs exclusively in the region of the orifices admittedly manifests itself there for example in the form of different spacings between the components, but it does not influence correct positioning of the functional parts of the components with respect to each other.
A further advantage is that the manner of connection to form a set of components in accordance with the invention does not give rise to a cumulative error and it is thus possible to achieve almost unlimited lengths of sets. The defined length and the axial positioning in respect of the needles in the glueing operation means that it is possible to avoid the previously necessary operation of subsequently operating on the ends of the components.
A third advantage is that it is possible to use bars of very small outside diameter, more specifically of outside diameters which are adequate exclusively for the required flexural stiffness of the bars, as there is no need for an internal space therein for an expansion element to be pushed therethrough.
As moreover no mechanical forces act on the components in the region of the orifices, the remaining width between the edge of the component and the orifice in the component can be very small and as a result the component can overall be of small width.
As generally the spacings between the individual components of the set must be very small, that is to say between 0.3 and 3 mm, it is important to use an application process for the adhesive, which ensures that the annular contact location or gap between the outside periphery of the bar and the outside surfaces of the components is wetted. Preferably in that respect that annular contact location is not only wetted over its entire periphery, but also the outside periphery of the bar will be wetted over the entire length of the spacing between the two components, and in particular the entire spacing between the two adjacent components should be filled with adhesive, around the bars, in order to achieve a connection which is as durable as possible, this naturally being the case at all the bars in a set. To achieve a component which is as flat as possible, there are generally two bars which are spaced in the longitudinal extent of the component.
For that purpose therefore the adhesive on being applied must either be of very low viscosity or it must be introduced at the adhesive location under a suitable pressure. Furthermore, a high surface tension on the part of the adhesive is a positive consideration in order to provide that as large an area as possible on both sides of the contact location is contacted by the adhesive, by virtue of the surface tension thereof. In particular, it is advantageous to use adhesives which can be applied in the form of a thick fluid or paste at a temperature of about 20xc2x0 C. and which then become very fluid upon heating to between about 150xc2x0 C. and 200xc2x0 C. and which at the same time harden very quickly. In order further to promote the glueing effect, it is also a positive consideration if the adhesive can penetrate into the orifice in the component, between the component and the bar. That is possible in particular when suitable cavities for that purpose are provided between the outside diameter of the bar and the inside diameter of the orifice in the component, for example by virtue of the size and/or the contour of the cross-section of the bar not being the same as that of the orifice and being correspondingly smaller.
That can be specifically implemented for example by the bar being provided with grooves extending in the longitudinal direction of the bar at the outside periphery of the bar while the orifice is of a smooth contour, or conversely, the inside periphery of the orifice has radially outwardly directed recesses while the outside diameter of the bar is of a smooth contour, irrespective of whether the basic contour is round, quadrangular, elliptical or the like, with a round contour generally being preferred for reasons related to manufacture.
A further option is that, in addition to the adhesive join, a join involving force-locking engagement or positively locking engagement between the outside diameter of the bar and the inside diameter of the orifice in a component is implemented before the glueing operation. That is possible for example by virtue of the mutually aligned orifices being of a pear-shaped contour and the bar being pushed into the wide end of that contour and then displaced in a direction towards the narrow end, and then becoming jammed therein in force-locking relationship by virtue of the wedging action which occurs. In the case of two orifices and bars, that displacement can be effected towards each other, with suitable alignment of the orifices.
c) Embodiment